KR20130047116A - Encapsulation sheet for a solarcell module and preparing process thereof - Google Patents

Abstract

(상기에서 R₁, R₂, R₃=H, C₁~C₈을 가지는 알킬 혹은 알콕시).
상기와 같이 구성되는 본 발명의 태양전지용 봉지재 시트 및 그 제조방법에서는 본 발명에 따른 특정한 포스페이트계 산화방지제를 사용하여 장기적으로 황변 현상을 용이하게 방지함으로, 태양전지 모듈의 발전효율과 봉지재의 유리 및 후면 보호 필름에 대한 접착성의 경시적 변화가 적게 하여 상기한 종래의 문제점을 해결하였을 뿐 아니라, 광안정제의 기능을 대신하여 첨가제 종류를 줄임으로써 경제적인 봉지재 시트를 제조할 수 있는 유용한 발명이다.The present invention relates to a solar cell encapsulant sheet used for the protection and encapsulation of a solar cell when manufacturing a solar cell module for photovoltaic power generation and a method of manufacturing the same, the solar cell encapsulant sheet of the present invention described above is EVA To 100 parts by weight of the copolymer is characterized in that it contains 0.01 to 1.0 parts by weight of an antioxidant containing a phosphate group represented by the formula (1):
[Formula 1]

(Alkyl or alkoxy having R ₁ , R ₂ , R ₃ = H, C ₁ -C ₈ in the above).
In the solar cell encapsulant sheet of the present invention and the manufacturing method thereof configured as described above by using a specific phosphate-based antioxidant according to the present invention to easily prevent yellowing phenomenon in the long term, the generation efficiency of the solar cell module and the glass of the encapsulant And it is a useful invention that can produce an economical encapsulant sheet by reducing the type of additives in place of the function of the light stabilizer, as well as solving the above-mentioned conventional problems by the small change over time of adhesion to the rear protective film. .

Description

Encapsulation sheet for solar cell and manufacturing method thereof

The present invention relates to a solar cell encapsulant sheet used for the protection and encapsulation of a solar cell when manufacturing a solar cell module for photovoltaic power generation, and a method of manufacturing the same, and more particularly, to providing various functionalities including a phosphate-based antioxidant. It is manufactured by mixing additives and EVA resins to prevent yellowing, and thus the solar cell encapsulant sheet and its manufacturing method which have reduced the generation efficiency of the solar cell module and the change of adhesion of the encapsulant to the glass and the back protective film over time. It is about.

In order to replace the exhausted energy and overcome environmental problems, various renewable energies are receiving attention. Of these energy sources, solar cells using solar energy show high growth because they are pollution-free, noise-free, and infinite supply energy.

Representative examples of solar cells include crystalline and amorphous silicon solar cells. In such a solar cell, a solar cell is a semiconductor device that converts sunlight into electrical energy using a photoelectric effect. Due to the characteristics of solar cells, they are always exposed to the harsh natural environment, so solar cells alone cannot be protected from rain, snow, high temperatures, low temperatures, and external shocks in the natural environment, and it is essential to undergo a modular process to protect them.

In general, the solar cell module is composed of a configuration in which two sheets of encapsulation material surround the solar cell between a glass substrate on the front side and a rear protective film on the rear side of the protective member. These solar cells are stacked in the order of glass substrate / encapsulation sheet / solar cell / encapsulation sheet / rear protective film, and the encapsulant sheet is completely melted by heating and pressure, so that sufficient mobility of the polymer is ensured. It is prepared through the pressurization and degassing process.

In general, the encapsulant sheet for a solar cell module consists of a sheet prepared after mixing a functional additive and a polymer to satisfy various requirements.

For such an encapsulant sheet, for example, Korean Patent No. 0928441 describes an adhesion aid such as a silane compound for adhesion to an EVA copolymer together with an organic peroxide, a crosslinking aid, an ultraviolet absorber, and an antioxidant. The sealing material sheet formed by adding is disclosed.

Degradation of polymers occurs in the polymer main chain or in the side chain, and free radicals are produced by heat, optical and mechanical external shocks, which react with oxygen immediately to form peroxide radicals, and the peroxides decompose themselves to other polymer molecules. It proceeds to the so-called automatic oxidation reaction. This automatic oxidation reaction continues to occur until a stable compound is produced.

The following three methods can suppress the oxidative degradation reaction. First, when the initiator is exposed to light such as ultraviolet rays as a prohibition of the initiation reaction, it is possible to control to some extent through an ultraviolet absorber or the like, but the action for the other two causes (thermal, mechanical external shock) is impossible. Second, as a prohibition of the chain reaction to act on the chain reaction to significantly reduce the rate can be remarkably effective if used in combination with the appropriate antioxidant according to the form. These include phenol derivatives and aromatic amine compounds, which are usually classified as primary antioxidants. Third, the decomposition of peroxides produced as peroxide decomposers into stable forms of radicals, which are classified as secondary antioxidants. In general, it is effective to use a combination of primary and secondary antioxidants to prevent oxidation by the generated radicals.

Hindered phenolics is one of the most commonly used primary antioxidants of thermoplastics, and BHT is representative. However, phenolic antioxidants such as BHT have a problem that despite their powerful effects, they deform themselves to form new chromophores and cause coloring in the sheet.

As the secondary antioxidant, hindered amines or phosphites are generally used. However, secondary antioxidants are limited in their effects, and in particular, amines may cause coloring in long-term use, which is not preferable for solar cells.

Patent Document 1: Republic of Korea Patent No. 0928441

Therefore, the present invention is proposed in view of the above-described technical problems, the main object of the present invention is to maintain the existing antioxidant function in the solar cell encapsulant sheet and to function as both primary and secondary antioxidants A solar cell encapsulation material capable of overcoming the reduction of solar cell efficiency over time by maintaining the long-term stability of the sheet through the use of an antioxidant without color change to maintain transparency, which is an important property in solar cells, for a long time. It is for providing a sheet.

Another object of the present invention is to provide a solar cell encapsulant sheet capable of securing economical efficiency by reducing the type of additive as much as possible by developing a function of an additive used in the production of a solar cell encapsulant sheet.

Another object of the present invention is to provide a manufacturing method that can more easily produce a solar cell encapsulant sheet having the above characteristics.

The present invention may also aim to achieve, in addition to the above-mentioned specific objects, other objects that can be readily derived by one of ordinary skill in the art from this and the overall description of this specification.

Solar cell encapsulant sheet of the present invention for achieving the above object;

To 100 parts by weight of the EVA copolymer is characterized in that 0.01 to 1.0 parts by weight of an antioxidant containing a phosphate group represented by the formula (1) is contained:

(Alkyl or alkoxy having R ₁ , R ₂ , R ₃ = H, C ₁ -C ₈ in the above).

In another configuration of the present invention, the EVA copolymer is characterized in that the vinyl acetate content is 26 to 33%.

In another configuration of the present invention, the sheet is prepared by adding 0.01 to 1.0 parts by weight of a crosslinking agent, 0.01 to 1.0 parts by weight of a crosslinking aid, 0.01 to 1.0 parts by weight of a silane coupling agent and 0.01 to 1.0 parts by weight of a UV absorber. It features.

Method for producing a solar cell encapsulant sheet of the present invention for achieving the above another object;

0.01 to 1.0 part by weight of an antioxidant including a phosphate group represented by Formula 1 above, 100 parts by weight of an EVA copolymer, additionally 0.01 to 1.0 part by weight of a crosslinking agent, 0.01 to 1.0 part by weight of a crosslinking aid, and 0.01 to 1.0 weight by weight of a silane coupling agent. In addition, by adding 0.01 to 1.0 parts by weight of the ultraviolet absorber, it is characterized in that it is prepared through a T-die or calendar method.

In the solar cell encapsulant sheet of the present invention and the manufacturing method thereof configured as described above by using a specific phosphate-based antioxidant according to the present invention to easily prevent yellowing phenomenon in the long term, the generation efficiency of the solar cell module and the glass of the encapsulant And it is a useful invention that can produce an economical encapsulant sheet by reducing the type of additives in place of the function of the light stabilizer, as well as solving the above-described conventional problems by the small change over time of the adhesion to the rear protective film. .

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail by preferable embodiment.

EVA encapsulant sheet for solar cells of the present invention contains an antioxidant comprising a phosphate group represented by the following formula:

(Alkyl or alkoxy having R ₁ , R ₂ , R ₃ = H, C ₁ -C ₈ in the above).

Compounds of the above formulas used according to the present invention have a large effect by acting simultaneously as primary and secondary antioxidants due to the characteristics of phenolic phosphate groups and do not form chromophores by self-conversion so that yellowing does not occur even after long-term use. There is an advantage. In addition, there is an advantage in that it is excellent in stability and good in compatibility with EVA resin, which is convenient for use.

According to another preferred embodiment of the present invention, there is provided an EVA encapsulant composition in which the crosslinking agent, the crosslinking aid, the silane coupling agent, the ultraviolet absorber, and the light stabilizer are further blended.

Moreover, the compounds used according to the present invention have the function of light stabilizers, and thus the use of additional light stabilizers provides the advantage that it is not necessary. Through this, it is possible to secure economical encapsulant by reducing the type of additives as well as securing long term reliability.

According to another preferred embodiment of the present invention, the EVA encapsulant sheet preferably has a vinyl acetate content of 25 to 35%.

As described above, additives such as a crosslinking agent, a crosslinking aid, a UV absorber, an antioxidant, and the like may be blended into the encapsulant sheet of the present invention as necessary, and the combination of the crosslinking agent or the crosslinking agent and the crosslinking aid may include a solar cell encapsulant. It is useful for crosslinking the EVA encapsulant sheet in a state suitable for a solar cell element and incorporated into the solar cell module, thereby maintaining heat resistance of the encapsulant sheet layer while preventing the melting in use at high temperatures. Can be given.

Compounds having phosphate groups used in the present invention can be prepared from various phenolic compounds or are commercially available.

In order to prepare a compound having a phosphate group of the present invention, as shown in the following reaction scheme, a phenol compound having various substituents and POCl ₃ are reacted in the presence of a base, and then the product is treated with a metal hydroxide to replace chlorine and then neutralized. You can get it through

Reaction:

The phosphate compound prepared by the above reaction scheme may be mixed with EVA resin and other additives to melt extrusion to prepare an encapsulant sheet.

The compound may be used in an amount of 0.01 to 1.0 parts by weight, preferably 0.05 to 0.5 parts by weight, because of excellent activity as an antioxidant.

In order to improve the gel fraction of the EVA resin and improve durability, a crosslinking aid may be added to the EVA resin. As a crosslinking adjuvant provided for this purpose, the crosslinking adjuvant which has trifunctional groups, such as a tri-allyl isocyanurate and a tri-allyl isocyanate, is mentioned. The amount of such crosslinking aid may be used in an amount of 5 parts by weight or less based on 100 parts by weight of the EVA copolymer resin, and preferably 0.01 to 1.0 parts by weight.

The encapsulant sheet of the present invention is embossed for the fairness when manufacturing a solar cell module after processing to a thickness of 200 to 800μm using a T-die extrusion method or a calender method by combining the EVA copolymer and various additives as described above. It can be prepared through.

The solar cell module using the solar cell module encapsulant sheet of the present invention is laminated in the order of the surface glass, the encapsulant sheet, the solar cell, the encapsulant sheet, the rear protective film, 100 to 100 by a vacuum laminator according to a predetermined rule. It can manufacture by heating and pressing at the temperature of 160 degreeC, 4-20 minutes of degassing time, 0.5-1 atmosphere of pressurization, and 5 to 60 minutes of pressurization time.

Hereinafter, the present invention will be described in more detail with reference to Preparation Examples, Examples, and Comparative Examples, but the following Examples are only intended to describe the present invention in detail and are not intended to limit the scope of the present invention.

Manufacturing example

BHT 220g (1 mol, Sigma-Aldrich Co.) was dissolved in THF (Sigma-Aldrich Co.) was added to 1000mL POCl ₃ 153g (1 mol, Sigma-Aldrich Co., Ltd.) made dichloro phosphate intermediate. To this was added 112 g of potassium hydroxide (2 mol, manufactured by Sigma Aldrich Co., Ltd.), followed by neutralization to prepare (2,6-di-t-butyl-4-methylphenyl) dihydrogen phosphate, a phosphate derivative of BHT.

Example 1

2,5-dimethyl-2,5-bis (t-butylperoxy) hexane (alkema) as a crosslinking agent based on 100 parts by weight of EVA copolymer (28% by weight of initial vinyl acetate content, 15 g / 10 minutes of melt flow rate) 1.0 parts by weight of Luperox 101), 0.8 parts by weight of tri-allyl isocyanurate (TAIC) as a crosslinking aid, 2-hydroxy-4-n-octoxybenzophenone (manufactured by CIBA) as a UV absorber , Chimassorb81) 0.1 part by weight, 0.1 parts by weight of bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate (Ciba, Tinuvin770DF) as an optical stabilizer, an antioxidant 0.1 part by weight of (2,6-di-t-butyl-4-methylphenyl) dihydrogen phosphate was blended and extruded at a temperature of less than 110 ° C. using a 104 mm diameter twin extruder to prepare a sheet having a thickness of 500 μm.

Example 2

It was prepared in the same manner as in Example 1 except that phenyl dihydrogen phosphate (manufactured by TCI Corporation) was used as an antioxidant.

Example 3

It was prepared in the same manner as in Example 1 except that 4- (t-pentyl) dihydrogen phosphate (manufactured by Sigma Aldrich) was used as the antioxidant.

Example 4

It was prepared as in Example 1 except that no light stabilizer was used.

Comparative Example 1

It was prepared in the same manner as in Example 1 except that BHT (manufactured by Sigma Aldrich Co., Ltd.) was used as an antioxidant.

Comparative Example 2

It was prepared as in Comparative Example 1 except that no light stabilizer was used.

Experimental Example

<Junction>

After laminating in order of surface glass, encapsulant sheet, encapsulant sheet, and rear protective film using the sheets prepared in Examples 1 to 4 and Comparative Examples 1 and 2, the temperature was 150 ° C. using an LM-50x50S vacuum laminator of NPC. Heated at 10 minutes to produce a mini module.

<Damp Heat Test>

The prepared mini-module was placed in a thermo-hygrostat at 85 ° C. and 85% condition, and yellowness (YI) was measured after 500 hours, 1000 hours, 1500 hours, and 2000 hours. Yellowness was carried out using a color difference meter SA4000 of Nippon Denshoku. The evaluation results are shown in Table 1 below.

Early
Yellow Degree (YI) After 500 hours
Yellow Degree (YI) After 1000 hours
Yellow Degree (YI) After 1500 hours
Yellow Degree (YI) After 2000 hours
Yellow Degree (YI) ΔYI Example 1 0.63 1.08 1.31 1.44 1.60 0.97 Example 2 0.68 1.15 1.37 1.52 1.89 1.21 Example 3 0.65 1.10 1.34 1.47 1.69 1.04 Example 4 0.64 1.12 1.34 1.42 1.65 1.01 Comparative Example 1 0.93 2.23 4.28 5.13 6.53 5.60 Comparative Example 2 1.03 3.83 5.07 8.01 9.78 8.75

In the experimental results, it can be seen that the value of ΔYI is much smaller than that of Comparative Example 1 in Examples 1 to 3 after 2000 hours. This result shows that when the present invention was used when the EVA sheet was prepared by adding the light stabilizer, the anti-yellowing effect was better than when BHT was used as the antioxidant. In the case of Example 1 and Example 4 there is almost no difference, this is a result showing that having an equivalent yellowing discoloration prevention effect even without adding a light stabilizer when formulating the EVA sheet by combining the compound according to the present invention. In addition, the ΔYI value in Comparative Example 2 is higher than that of Comparative Example 1, which is a result showing that the anti-yellowing effect of the yellowing is reduced when the BHT antioxidant is not added to the light stabilizer.

In these results, the compound according to the present invention has an excellent effect of preventing yellowing coloration compared to the conventional BHT antioxidant, and instead of the function of the light stabilizer, there is an effect of preventing the efficiency decrease over time of the solar cell, additives It can be seen that by reducing the type of economical sealing material sheet can be produced.

Claims (4)

Solar cell encapsulant sheet, characterized in that 0.01 to 1.0 parts by weight of an antioxidant containing a phosphate group represented by the following formula (1) to 100 parts by weight of the EVA copolymer:
[Formula 1]

(Alkyl or alkoxy having R ₁ , R ₂ , R ₃ = H, C ₁ -C ₈ in the above).
The encapsulant sheet for solar cells of claim 1, wherein the EVA copolymer has a vinyl acetate content of 26 to 33%.
According to claim 1 or 2, wherein the sheet is prepared by adding 0.01 to 1.0 parts by weight of crosslinking agent, 0.01 to 1.0 parts by weight of crosslinking aid, 0.01 to 1.0 parts by weight of silane coupling agent, 0.01 to 1.0 parts by weight of ultraviolet absorber. Solar cell encapsulant sheet, characterized in that.
0.01 to 1.0 parts by weight of an antioxidant including a phosphate group represented by the following formula (1) to 100 parts by weight of an EVA copolymer, additionally 0.01 to 1.0 parts by weight of a crosslinking agent, 0.01 to 1.0 parts by weight of a crosslinking aid, and 0.01 to 1.0 weight of a silane coupling agent. Part, by adding 0.01 to 1.0 parts by weight of the ultraviolet absorber, manufacturing method of a solar cell encapsulant sheet, characterized in that it is manufactured through a T-die or calendar method:
[Formula 1]

(Alkyl or alkoxy having R ₁ , R ₂ , R ₃ = H, C ₁ -C ₈ in the above).